1. Field of the Disclosure
The disclosure relates to power converters, and more particularly, to control circuits for isolated power converters.
2. Background
Switch mode power converters are widely used in household and industrial appliances for converting a low frequency (e.g., 50 Hz or 60 Hz) high voltage alternating current (ac) input voltage to a required level of direct current (dc) output voltage. For example, switch mode power converters may be included in commonly used electronic devices, such as battery chargers for mobile electronic devices. Various types of switch mode power converters are popular because of their well regulated output, high efficiency, and small size along with their safety and protection features. Popular topologies of switch mode power converters include flyback, forward, push-pull, and full bridge, among many others including resonant types.
A challenge in the market of switch mode power converters is improving the efficiency of the power converter while maintaining high performance. A typical power converter may include a variety of circuit components that dissipate power during operation. For example, power converters may include control circuits that sense output voltage and control power switching in the switch mode power converter to regulate the output voltage to a desired value. Some circuit components of the power converter (e.g., the control circuits) may be powered from a voltage level that is greater than required for proper operation. Powering circuit components of the power converter using a voltage level that is greater than required may lead to excess power dissipation and reduction in the overall efficiency of the power converter.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in commercially feasible embodiments are often not depicted in order to facilitate a less obstructed view of the various embodiments of the present disclosure.